1. Field of the Invention
The present invention relates to a laminate type LC composite device, and more particularly, to a laminate type LC composite device which is used for a filter circuit.
2. Description of Related Art
FIGS. 15 and 16 show LC composite devices of prior art. FIG. 15 is an electric equivalent circuit diagram of a T type LC filter. In this LC filter, between an input electrode 67 and an output electrode 68, coils 62 and 63 are connected in series, and a capacitor 64 is connected in parallel. Stray capacitances of C.sub.10 are generated in parallel with the coils 62 and 63 respectively. Numeral 69 denotes a grounding electrode.
FIG. 16 is an electric equivalent circuit diagram of a .pi. type LC filter. In this LC filter, between an input electrode 77 and an output electrode 78, a coil 72 is connected in series, and capacitors 73 and 74 are connected in parallel. A stray capacitance of C.sub.11 is generated in parallel with the coil 72. Numerals 79a and 79b denote grounding electrodes.
In these T type and .pi. type LC filters, the inductance and the stray capacitance C.sub.10 of the coil 62, the inductance and the stray capacitance C.sub.10 of the coil 63, and the inductance and the stray capacitance C.sub.11 of the coil 72 resonate respectively. In a high-frequency area having frequencies above the resonance frequency, the noise eliminating function of the coils 62, 63 and 72 becomes weak, and noise currents flowing in the stray capacitances C.sub.10 and C.sub.11 increase. Thus, these LC filters have a disadvantage that in a high-frequency area over the resonance frequency, the noise eliminating function becomes weak because of a small insertion loss.